251
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Saliba E, Sesti EL, Alaniva N, Barnes AB. Pulsed Electron Decoupling and Strategies for Time Domain Dynamic Nuclear Polarization with Magic Angle Spinning. J Phys Chem Lett 2018; 9:5539-5547. [PMID: 30180584 PMCID: PMC6151657 DOI: 10.1021/acs.jpclett.8b01695] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 09/04/2018] [Indexed: 05/05/2023]
Abstract
Magic angle spinning (MAS) dynamic nuclear polarization (DNP) is widely used to increase nuclear magnetic resonance (NMR) signal intensity. Frequency-chirped microwaves yield superior control of electron spins and are expected to play a central role in the development of DNP MAS experiments. Time domain electron control with MAS has considerable promise to improve DNP performance at higher fields and temperatures. We have recently demonstrated that pulsed electron decoupling using frequency-chirped microwaves improves MAS DNP experiments by partially attenuating detrimental hyperfine interactions. The continued development of pulsed electron decoupling will enable a new suite of MAS DNP experiments that transfer polarization directly to observed spins. Time domain DNP transfers to nuclear spins in conjunction with pulsed electron decoupling is described as a viable avenue toward DNP-enhanced, high-resolution NMR spectroscopy over a range of temperatures from <6 to 320 K.
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Affiliation(s)
- Edward
P. Saliba
- Department of Chemistry, Washington
University in St. Louis, St. Louis, Missouri 63130, United States
| | - Erika L. Sesti
- Department of Chemistry, Washington
University in St. Louis, St. Louis, Missouri 63130, United States
| | - Nicholas Alaniva
- Department of Chemistry, Washington
University in St. Louis, St. Louis, Missouri 63130, United States
| | - Alexander B. Barnes
- Department of Chemistry, Washington
University in St. Louis, St. Louis, Missouri 63130, United States
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252
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Martin RW, Kelly JE, Kelz JI. Advances in instrumentation and methodology for solid-state NMR of biological assemblies. J Struct Biol 2018; 206:73-89. [PMID: 30205196 DOI: 10.1016/j.jsb.2018.09.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 07/08/2018] [Accepted: 09/06/2018] [Indexed: 01/11/2023]
Abstract
Many advances in instrumentation and methodology have furthered the use of solid-state NMR as a technique for determining the structures and studying the dynamics of molecules involved in complex biological assemblies. Solid-state NMR does not require large crystals, has no inherent size limit, and with appropriate isotopic labeling schemes, supports solving one component of a complex assembly at a time. It is complementary to cryo-EM, in that it provides local, atomic-level detail that can be modeled into larger-scale structures. This review focuses on the development of high-field MAS instrumentation and methodology; including probe design, benchmarking strategies, labeling schemes, and experiments that enable the use of quadrupolar nuclei in biomolecular NMR. Current challenges facing solid-state NMR of biological assemblies and new directions in this dynamic research area are also discussed.
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Affiliation(s)
- Rachel W Martin
- Department of Chemistry, University of California, Irvine 92697-2025, United States; Department of Molecular Biology and Biochemistry, University of California, Irvine 92697-3900, United States.
| | - John E Kelly
- Department of Chemistry, University of California, Irvine 92697-2025, United States
| | - Jessica I Kelz
- Department of Chemistry, University of California, Irvine 92697-2025, United States
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253
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Rossini AJ. Materials Characterization by Dynamic Nuclear Polarization-Enhanced Solid-State NMR Spectroscopy. J Phys Chem Lett 2018; 9:5150-5159. [PMID: 30107121 DOI: 10.1021/acs.jpclett.8b01891] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
High-resolution solid-state NMR spectroscopy is a powerful tool for the study of organic and inorganic materials because it can directly probe the symmetry and structure at nuclear sites, the connectivity/bonding of atoms and precisely measure interatomic distances. However, NMR spectroscopy is hampered by intrinsically poor sensitivity; consequently, the application of NMR spectroscopy to many solid materials is often infeasible. High-field dynamic nuclear polarization (DNP) has emerged as a technique to routinely enhance the sensitivity of solid-state NMR experiments by 1-3 orders of magnitude. This Perspective gives a general overview of how DNP-enhanced solid-state NMR spectroscopy can be applied to a variety of inorganic and organic materials. DNP-enhanced solid-state NMR experiments provide unique insights into the molecular structure, which makes it possible to form structure-activity relationships that ultimately assist in the rational design and improvement of materials.
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Affiliation(s)
- Aaron J Rossini
- Department of Chemistry , Iowa State University , Ames , Iowa 50011 , United States
- U.S. DOE Ames Laboratory , Ames , Iowa 50011 , United States
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254
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Geiger MA, Jagtap AP, Kaushik M, Sun H, Stöppler D, Sigurdsson ST, Corzilius B, Oschkinat H. Efficiency of Water-Soluble Nitroxide Biradicals for Dynamic Nuclear Polarization in Rotating Solids at 9.4 T: bcTol-M and cyolyl-TOTAPOL as New Polarizing Agents. Chemistry 2018; 24:13485-13494. [PMID: 29741214 DOI: 10.1002/chem.201801251] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 05/01/2018] [Indexed: 12/24/2022]
Abstract
Nitroxide biradicals are very efficient polarizing agents in magic angle spinning (MAS) cross effect (CE) dynamic nuclear polarization (DNP) nuclear magnetic resonance (NMR). Many recently synthesized, new radicals show superior DNP-efficiency in organic solvents but suffer from insufficient solubility in water or glycerol/water for biological applications. We report DNP efficiencies for two new radicals, the water-soluble bcTol-M and cyolyl-TOTAPOL, and include a comparison with three known biradicals, TOTAPOL, bcTol, and AMUPol. They differ by linker groups, featuring either a 3-aminopropane-1,2-diol or a urea tether, or by the structure of the alkyl substituents that flank the nitroxide groups. For evaluating their performances, we measured both signal enhancements ϵ and DNP-enhanced sensitivity κ, and compared the results to electron spin relaxation data recorded at the same magnetic field strength (9.4 T). In our study, differences in DNP efficiency correlate with changes in the nuclear polarization dynamics rather than electron relaxation. The ratios of their individual ϵ and κ differ by up to 20 %, which is explained by starkly different nuclear polarization build-up rates. For the radicals compared here empirically, using proline standard solutions, the new radical bcTol-M performs best while being most soluble in water/glycerol mixtures.
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Affiliation(s)
- Michel-Andreas Geiger
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert Roessle-Str. 10, 13125, Berlin, Germany
| | - Anil P Jagtap
- Department of Chemistry, Science Institute, University of Iceland, Dunhaga 3, 107, Reykjavik, Iceland
| | - Monu Kaushik
- Institut für Physikalische und Theoretische Chemie, Institut für Biophysikalische Chemie, und Biomolekulares Magnetresonanzzentrum (BMRZ), Goethe-Universität Frankfurt, Max-van-Laue-Str.7-9, 60438, Frankfurt am Main, Germany
| | - Han Sun
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert Roessle-Str. 10, 13125, Berlin, Germany
| | - Daniel Stöppler
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert Roessle-Str. 10, 13125, Berlin, Germany
| | - Snorri T Sigurdsson
- Department of Chemistry, Science Institute, University of Iceland, Dunhaga 3, 107, Reykjavik, Iceland
| | - Björn Corzilius
- Institut für Physikalische und Theoretische Chemie, Institut für Biophysikalische Chemie, und Biomolekulares Magnetresonanzzentrum (BMRZ), Goethe-Universität Frankfurt, Max-van-Laue-Str.7-9, 60438, Frankfurt am Main, Germany
| | - Hartmut Oschkinat
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert Roessle-Str. 10, 13125, Berlin, Germany
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255
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Paul G, Bisio C, Braschi I, Cossi M, Gatti G, Gianotti E, Marchese L. Combined solid-state NMR, FT-IR and computational studies on layered and porous materials. Chem Soc Rev 2018; 47:5684-5739. [PMID: 30014075 DOI: 10.1039/c7cs00358g] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Understanding the structure-property relationship of solids is of utmost relevance for efficient chemical processes and technological applications in industries. This contribution reviews the concept of coupling three well-known characterization techniques (solid-state NMR, FT-IR and computational methods) for the study of solid state materials which possess 2D and 3D architectures and discusses the way it will benefit the scientific communities. It highlights the most fundamental and applied aspects of the proactive combined approach strategies to gather information at a molecular level. The integrated approach involving multiple spectroscopic and computational methods allows achieving an in-depth understanding of the surface, interfacial and confined space processes that are beneficial for the establishment of structure-property relationships. The role of ssNMR/FT-IR spectroscopic properties of probe molecules in monitoring the strength and distribution of catalytic active sites and their accessibility at the porous/layered surface is discussed. Both experimental and theoretical aspects will be considered by reporting relevant examples. This review also identifies and discusses the progress, challenges and future prospects in the field of synthesis and applications of layered and porous solids.
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Affiliation(s)
- Geo Paul
- Department of Science and Technological Innovation, Università del Piemonte Orientale, Viale T. Michel 11, 15121 Alessandria, Italy.
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256
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Ashbrook SE, Hodgkinson P. Perspective: Current advances in solid-state NMR spectroscopy. J Chem Phys 2018; 149:040901. [PMID: 30068173 DOI: 10.1063/1.5038547] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
In contrast to the rapid and revolutionary impact of solution-state Nuclear Magnetic Resonance (NMR) on modern chemistry, the field of solid-state NMR has matured more slowly. This reflects the major technical challenges of much reduced spectral resolution and sensitivity in solid-state as compared to solution-state spectra, as well as the relative complexity of the solid state. In this perspective, we outline the technique developments that have pushed resolution to intrinsic limits and the approaches, including ongoing major developments in the field of Dynamic Nuclear Polarisation, that have enhanced spectral sensitivity. The information on local structure and dynamics that can be obtained using these gains in sensitivity and resolution is illustrated with a diverse range of examples from large biomolecules to energy materials and pharmaceuticals and from both ordered and highly disordered materials. We discuss how parallel developments in quantum chemical calculation, particularly density functional theory, have enabled experimental data to be translated directly into information on local structure and dynamics, giving rise to the developing field of "NMR crystallography."
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Affiliation(s)
- Sharon E Ashbrook
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, St Andrews KY16 9ST, United Kingdom
| | - Paul Hodgkinson
- Department of Chemistry, Durham University, Durham DH1 4RD, United Kingdom
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257
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Korchak S, Mamone S, Glöggler S. Over 50 % 1H and 13C Polarization for Generating Hyperpolarized Metabolites-A para-Hydrogen Approach. ChemistryOpen 2018; 7:672-676. [PMID: 30191091 PMCID: PMC6121117 DOI: 10.1002/open.201800086] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Indexed: 11/23/2022] Open
Abstract
para‐Hydrogen‐induced polarization (PHIP) is a method to rapidly generate hyperpolarized compounds, enhancing the signal of nuclear magnetic resonance (NMR) experiments by several thousand‐fold. The hyperpolarization of metabolites and their use as contrast agents in vivo is an emerging diagnostic technique. High degrees of polarization and extended polarization lifetime are necessary requirements for the detection of metabolites in vivo. Here, we present pulsed NMR methods for obtaining hyperpolarized magnetization in two metabolites. We demonstrate that the hydrogenation with para‐hydrogen of perdeuterated vinyl acetate allows us to create hyperpolarized ethyl acetate with close to 60 % 1H two‐spin order. With nearly 100 % efficiency, this order can either be transferred to 1H in‐phase magnetization or 13C magnetization of the carbonyl function. Close to 60 % polarization is experimentally verified for both nuclei. Cleavage of the ethyl acetate precursor in a 20 s reaction yields ethanol with approximately 27 % 1H polarization and acetate with around 20 % 13C polarization. This development will open new opportunities to generate metabolic contrast agents in less than one minute.
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Affiliation(s)
- Sergey Korchak
- NMR Signal Enhancement Group Max-Planck-Institute for Biophysical Chemistry Am Faßberg 11 37077 Göttingen Germany.,Center for Biostructural Imaging of Neurodegeneration Von-Siebold-Straße 3A 37075 Göttingen Germany
| | - Salvatore Mamone
- NMR Signal Enhancement Group Max-Planck-Institute for Biophysical Chemistry Am Faßberg 11 37077 Göttingen Germany.,Center for Biostructural Imaging of Neurodegeneration Von-Siebold-Straße 3A 37075 Göttingen Germany
| | - Stefan Glöggler
- NMR Signal Enhancement Group Max-Planck-Institute for Biophysical Chemistry Am Faßberg 11 37077 Göttingen Germany.,Center for Biostructural Imaging of Neurodegeneration Von-Siebold-Straße 3A 37075 Göttingen Germany
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258
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Zhao L, Pinon AC, Emsley L, Rossini AJ. DNP-enhanced solid-state NMR spectroscopy of active pharmaceutical ingredients. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2018; 56:583-609. [PMID: 29193278 DOI: 10.1002/mrc.4688] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Revised: 11/15/2017] [Accepted: 11/19/2017] [Indexed: 06/07/2023]
Abstract
Solid-state NMR spectroscopy has become a valuable tool for the characterization of both pure and formulated active pharmaceutical ingredients (APIs). However, NMR generally suffers from poor sensitivity that often restricts NMR experiments to nuclei with favorable properties, concentrated samples, and acquisition of one-dimensional (1D) NMR spectra. Here, we review how dynamic nuclear polarization (DNP) can be applied to routinely enhance the sensitivity of solid-state NMR experiments by one to two orders of magnitude for both pure and formulated APIs. Sample preparation protocols for relayed DNP experiments and experiments on directly doped APIs are detailed. Numerical spin diffusion models illustrate the dependence of relayed DNP enhancements on the relaxation properties and particle size of the solids and can be used for particle size determination when the other factors are known. We then describe the advanced solid-state NMR experiments that have been enabled by DNP and how they provide unique insight into the molecular and macroscopic structure of APIs. For example, with large sensitivity gains provided by DNP, natural isotopic abundance, 13 C-13 C double-quantum single-quantum homonuclear correlation NMR spectra of pure APIs can be routinely acquired. DNP also enables solid-state NMR experiments with unreceptive quadrupolar nuclei such as 2 H, 14 N, and 35 Cl that are commonly found in APIs. Applications of DNP-enhanced solid-state NMR spectroscopy for the molecular level characterization of low API load formulations such as commercial tablets and amorphous solid dispersions are described. Future perspectives for DNP-enhanced solid-state NMR experiments on APIs are briefly discussed.
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Affiliation(s)
- Li Zhao
- Department of Chemistry, Iowa State University, Ames, IA, USA
- US DOE Ames Laboratory, Ames, IA, USA
| | - Arthur C Pinon
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Lyndon Emsley
- Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Aaron J Rossini
- Department of Chemistry, Iowa State University, Ames, IA, USA
- US DOE Ames Laboratory, Ames, IA, USA
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259
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Meier B. Quantum-rotor-induced polarization. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2018; 56:610-618. [PMID: 29460384 DOI: 10.1002/mrc.4725] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 02/05/2018] [Accepted: 02/10/2018] [Indexed: 06/08/2023]
Abstract
Quantum-rotor-induced polarization is closely related to para-hydrogen-induced polarization. In both cases, the hyperpolarized spin order derives from rotational interaction and the Pauli principle by which the symmetry of the rotational ground state dictates the symmetry of the associated nuclear spin state. In quantum-rotor-induced polarization, there may be several spin states associated with the rotational ground state, and the hyperpolarization is typically generated by hetero-nuclear cross-relaxation. This review discusses preconditions for quantum-rotor-induced polarization for both the 1-dimensional methyl rotor and the asymmetric rotor H217 O@C60 , that is, a single water molecule encapsulated in fullerene C60 . Experimental results are presented for both rotors.
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Affiliation(s)
- Benno Meier
- School of Chemistry, University of Southampton, Southampton, UK
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260
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Can TV, McKay JE, Weber RT, Yang C, Dubroca T, van Tol J, Hill S, Griffin RG. Frequency-Swept Integrated and Stretched Solid Effect Dynamic Nuclear Polarization. J Phys Chem Lett 2018; 9:3187-3192. [PMID: 29756781 PMCID: PMC8253171 DOI: 10.1021/acs.jpclett.8b01002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We investigate a new time domain approach to dynamic nuclear polarization (DNP), the frequency-swept integrated solid effect (FS-ISE), utilizing a high power, broadband 94 GHz (3.35 T) pulse EPR spectrometer. The bandwidth of the spectrometer enabled measurement of the DNP Zeeman frequency/field profile that revealed two dominant polarization mechanisms, the expected ISE, and a recently observed mechanism, the stretched solid effect (S2E). At 94 GHz, despite the limitations in the microwave chirp pulse length (10 μs) and the repetition rate (2 kHz), we obtained signal enhancements up to ∼70 for the S2E and ∼50 for the ISE. The results successfully demonstrate the viability of the FS-ISE and S2E DNP at a frequency 10 times higher than previous studies. Our results also suggest that these approaches are candidates for implementation at higher magnetic fields.
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Affiliation(s)
- T. V. Can
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - J. E. McKay
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
| | - R. T. Weber
- Bruker BioSpin Corporation, Billerica, Massachusetts 01821, United States
| | - C. Yang
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - T. Dubroca
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
| | - J. van Tol
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
| | - S. Hill
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
- Department of Physics, Florida State University, Tallahassee, Florida 32310, United States
| | - R. G. Griffin
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Corresponding Author
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261
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Chakrabarty T, Goldin N, Feintuch A, Houben L, Leskes M. Paramagnetic Metal-Ion Dopants as Polarization Agents for Dynamic Nuclear Polarization NMR Spectroscopy in Inorganic Solids. Chemphyschem 2018; 19:2139-2142. [DOI: 10.1002/cphc.201800462] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Indexed: 11/05/2022]
Affiliation(s)
- Tanmoy Chakrabarty
- Department of Materials and Interfaces; Weizmann Institute of Science; Rehovot 761000 Israel
| | - Nir Goldin
- Department of Materials and Interfaces; Weizmann Institute of Science; Rehovot 761000 Israel
| | - Akiva Feintuch
- Department of Biological and Chemical Physics; Weizmann Institute of Science; Rehovot 761000 Israel
| | - Lothar Houben
- Department of Chemical Research Support; Weizmann Institute of Science; Rehovot 761000 Israel
| | - Michal Leskes
- Department of Materials and Interfaces; Weizmann Institute of Science; Rehovot 761000 Israel
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262
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Kaminker I, Han S. Amplification of Dynamic Nuclear Polarization at 200 GHz by Arbitrary Pulse Shaping of the Electron Spin Saturation Profile. J Phys Chem Lett 2018; 9:3110-3115. [PMID: 29775537 DOI: 10.1021/acs.jpclett.8b01413] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Dynamic nuclear polarization (DNP) takes center stage in nuclear magnetic resonance (NMR) as a tool to amplify its signal by orders of magnitude through the transfer of polarization from electron to nuclear spins. In contrast to modern NMR and electron paramagnetic resonance (EPR) that extensively rely on pulses for spin manipulation in the time domain, the current mainstream DNP technology exclusively relies on monochromatic continuous wave (CW) irradiation. This study introduces arbitrary phase shaped pulses that constitute a train of coherent chirp pulses in the time domain at 200 GHz (7 T) to dramatically enhance the saturation bandwidth and DNP performance compared to CW DNP, yielding up to 500-fold in NMR signal enhancements. The observed improvement is attributed to the recruitment of additional electron spins contributing to DNP via the cross-effect mechanism, as experimentally confirmed by two-frequency pump-probe electron-electron double resonance (ELDOR).
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263
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Cao W, Wang WD, Xu HS, Sergeyev IV, Struppe J, Wang X, Mentink-Vigier F, Gan Z, Xiao MX, Wang LY, Chen GP, Ding SY, Bai S, Wang W. Exploring Applications of Covalent Organic Frameworks: Homogeneous Reticulation of Radicals for Dynamic Nuclear Polarization. J Am Chem Soc 2018; 140:6969-6977. [PMID: 29799739 PMCID: PMC6045815 DOI: 10.1021/jacs.8b02839] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Rapid progress has been witnessed in the past decade in the fields of covalent organic frameworks (COFs) and dynamic nuclear polarization (DNP). In this contribution, we bridge these two fields by constructing radical-embedded COFs as promising DNP agents. Via polarization transfer from unpaired electrons to nuclei, DNP realizes significant enhancement of NMR signal intensities. One of the crucial issues in DNP is to screen for suitable radicals to act as efficient polarizing agents, the basic criteria for which are homogeneous distribution and fixed orientation of unpaired electrons. We therefore envisioned that the crystalline and porous structures of COFs, if evenly embedded with radicals, may work as a new "crystalline sponge" for DNP experiments. As a proof of concept, we constructed a series of proxyl-radical-embedded COFs (denoted as PR( x)-COFs) and successfully applied them to achieve substantial DNP enhancement. Benefiting from the bottom-up and multivariate synthetic strategies, proxyl radicals have been covalently reticulated, homogeneously distributed, and rigidly embedded into the crystalline and mesoporous frameworks with adjustable concentration ( x%). Excellent performance of PR( x)-COFs has been observed for DNP 1H, 13C, and 15N solid-state NMR enhancements. This contribution not only realizes the direct construction of radical COFs from radical monomers, but also explores the new application of COFs as DNP polarizing agents. Given that many radical COFs can therefore be rationally designed and facilely constructed with well-defined composition, distribution, and pore size, we expect that our effort will pave the way for utilizing radical COFs as standard polarizing agents in DNP NMR experiments.
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Affiliation(s)
- Wei Cao
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , Gansu 730000 , China
| | - Wei David Wang
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , Gansu 730000 , China
| | - Hai-Sen Xu
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , Gansu 730000 , China
| | - Ivan V Sergeyev
- Bruker BioSpin Corporation , 15 Fortune Drive , Billerica , Massachusetts 01821 , United States
| | - Jochem Struppe
- Bruker BioSpin Corporation , 15 Fortune Drive , Billerica , Massachusetts 01821 , United States
| | - Xiaoling Wang
- National High Magnetic Field Laboratory , Florida State University , Tallahassee , Florida 32310 , United States
| | - Frederic Mentink-Vigier
- National High Magnetic Field Laboratory , Florida State University , Tallahassee , Florida 32310 , United States
| | - Zhehong Gan
- National High Magnetic Field Laboratory , Florida State University , Tallahassee , Florida 32310 , United States
| | - Ming-Xing Xiao
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , Gansu 730000 , China
| | - Lu-Yao Wang
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , Gansu 730000 , China
| | - Guo-Peng Chen
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , Gansu 730000 , China
| | - San-Yuan Ding
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , Gansu 730000 , China
| | - Shi Bai
- Department of Chemistry and Biochemistry , University of Delaware , Newark , Delaware 19716 , United States
| | - Wei Wang
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , Gansu 730000 , China
- Collaborative Innovation Center of Chemical Science and Engineering , Tianjin 300071 , China
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264
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Timm KN, Miller JJ, Henry JA, Tyler DJ. Cardiac applications of hyperpolarised magnetic resonance. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2018; 106-107:66-87. [PMID: 31047602 DOI: 10.1016/j.pnmrs.2018.05.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 05/14/2018] [Accepted: 05/29/2018] [Indexed: 05/05/2023]
Abstract
Cardiovascular disease is the leading cause of death world-wide. It is increasingly recognised that cardiac pathologies show, or may even be caused by, changes in metabolism, leading to impaired cardiac energetics. The heart turns over 15 times its own weight in ATP every day and thus relies heavily on the availability of substrates and on efficient oxidation to generate this ATP. A number of old and emerging drugs that target different aspects of metabolism are showing promising results with regard to improved cardiac outcomes in patients. A non-invasive imaging technique that could assess the role of different aspects of metabolism in heart disease, as well as measure changes in cardiac energetics due to treatment, would be valuable in the routine clinical care of cardiac patients. Hyperpolarised magnetic resonance spectroscopy and imaging have revolutionised metabolic imaging, allowing real-time metabolic flux assessment in vivo for the first time. In this review we summarise metabolism in the healthy and diseased heart, give an introduction to the hyperpolarisation technique, 'dynamic nuclear polarisation' (DNP), and review the preclinical studies that have thus far explored healthy cardiac metabolism and different models of human heart disease. We furthermore show what advances have been made to translate this technique into the clinic, what technical challenges still remain and what unmet clinical needs and unexplored metabolic substrates still need to be assessed by researchers in this exciting and fast-moving field.
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Affiliation(s)
- Kerstin N Timm
- Department of Physiology, Anatomy and Genetics, University of Oxford, UK.
| | - Jack J Miller
- Department of Physiology, Anatomy and Genetics, University of Oxford, UK; Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Oxford, UK; Clarendon Laboratory, Department of Physics, University of Oxford, UK.
| | - John A Henry
- Department of Physiology, Anatomy and Genetics, University of Oxford, UK.
| | - Damian J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, UK; Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Oxford, UK.
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265
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Equbal A, Li Y, Leavesley A, Huang S, Rajca S, Rajca A, Han S. Truncated Cross Effect Dynamic Nuclear Polarization: An Overhauser Effect Doppelgänger. J Phys Chem Lett 2018; 9:2175-2180. [PMID: 29630375 PMCID: PMC6426302 DOI: 10.1021/acs.jpclett.8b00751] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The discovery of a truncated cross-effect (CE) in dynamic nuclear polarization (DNP) NMR that has the features of an Overhauser-effect DNP (OE-DNP) is reported here. The apparent OE-DNP, where minimal μw power achieved optimum enhancement, was observed when doping Trityl-OX063 with a pyrroline nitroxide radical that possesses electron-withdrawing tetracarboxylate substituents (tetracarboxylate-ester-pyrroline or TCP) in vitrified water/glycerol at 6.9 T and at 3.3 to 85 K, in apparent contradiction to expectations. While the observations are fully consistent with OE-DNP, we discover that a truncated cross-effect ( tCE) is the underlying mechanism, owing to TCP's shortened T1e. We take this observation as a guideline and demonstrate that a crossover from CE to tCE can be replicated by simulating the CE of a narrow-line (Trityl-OX063) and a broad-line (TCP) radical pair, with a significantly shortened T1e of the broad-line radical.
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Affiliation(s)
- Asif Equbal
- Department of Chemistry and Biochemistry , University of California, Santa Barbara , Santa Barbara , California 93106 , United States
| | - Yuanxin Li
- Department of Chemistry and Biochemistry , University of California, Santa Barbara , Santa Barbara , California 93106 , United States
| | - Alisa Leavesley
- Department of Chemistry and Biochemistry , University of California, Santa Barbara , Santa Barbara , California 93106 , United States
| | - Shengdian Huang
- Department of Chemistry , University of Nebraska , Lincoln , Nebraska 68588-0304 , United States
| | - Suchada Rajca
- Department of Chemistry , University of Nebraska , Lincoln , Nebraska 68588-0304 , United States
| | - Andrzej Rajca
- Department of Chemistry , University of Nebraska , Lincoln , Nebraska 68588-0304 , United States
| | - Songi Han
- Department of Chemistry , University of Nebraska , Lincoln , Nebraska 68588-0304 , United States
- Department of Chemical Engineering , University of California, Santa Barbara , Santa Barbara , California 93106 , United States
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266
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Wittmann JJ, Eckardt M, Harneit W, Corzilius B. Electron-driven spin diffusion supports crossing the diffusion barrier in MAS DNP. Phys Chem Chem Phys 2018; 20:11418-11429. [PMID: 29645035 DOI: 10.1039/c8cp00265g] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Dynamic nuclear polarization (DNP) can be applied to enhance the sensitivity of solid-state NMR experiments by several orders of magnitude due to microwave-driven transfer of spin polarization from unpaired electrons to nuclei. While the underlying quantum mechanical aspects are sufficiently well understood on a microscopic level, the exact description of the large-scale spin dynamics, usually involving hundreds to thousands of nuclear spins per electron, is still lacking consensus. Generally, it is assumed that nuclear hyperpolarization can only be observed on nuclei which do not experience strong influence of the unpaired electrons and thus being significantly removed from the paramagnetic polarizing agents. At the same time, sufficiently strong hyperfine interaction is required for DNP transfer. Therefore, efficient nuclear spin diffusion from the strongly-interacting nuclei to the NMR-observable bulk is considered to be essential for efficient nuclear hyperpolarization. Based on experimental results obtained on the endohedral fullerene N@C60 as a polarizing agent sparsely diluted in C60, we discuss the effect of the spin-diffusion barrier. We introduce electron-driven spin diffusion (EDSD) as a novel mechanism for nuclear polarization transfer in the proximity of an electron spin which is particularly relevant under magic-angle spinning (MAS) DNP conditions.
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Affiliation(s)
- Johannes J Wittmann
- Institute of Physical and Theoretical Chemistry, Institute of Biophysical Chemistry, and Biomolecular Magnetic Resonance Center (BMRZ), Goethe University Frankfurt, Max-von-Laue-Str. 7-9, 60438 Frankfurt, Germany.
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267
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Kundu K, Feintuch A, Vega S. Electron-Electron Cross-Relaxation and Spectral Diffusion during Dynamic Nuclear Polarization Experiments on Solids. J Phys Chem Lett 2018; 9:1793-1802. [PMID: 29553271 DOI: 10.1021/acs.jpclett.8b00090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Recently it has been shown that experimental electron-electron double resonance (ELDOR) spectra of amorphous glasses containing free radicals with inhomogeneously broadened electron paramagnetic resonance (EPR) spectra can be analyzed using a set of coupled rate equations for the electron polarizations of frequency bins composing these spectra, named the eSD (electron spectral diffusion) model. The rate matrix defining these equations has elements depending on the microwave, the spin-lattice relaxation rates and on eSD rate constants responsible for polarization exchange. In this study, we show that in addition to the static dipolar flip-flop terms in the Hamiltonian a zero-quantum electron cross-relaxation mechanism can be responsible for the polarization exchange process in our samples. This conclusion was reached by calculating the EPR lineshapes of a system of 11 coupled electrons exposed to microwave irradiation using an eigenstate population rate equation derived from the spin density vector rate equation in Liouville space. These equations involve all terms of the Hamiltonian and in addition rate constants representing longitudinal relaxation and cross-relaxation mechanisms as well as MW irradiation. The results of these calculations are compared with the results obtained from the eSD model.
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Affiliation(s)
- Krishnendu Kundu
- Department of Chemical and Biological Physics , Weizmann Institute of Science , Rehovot - 76100 , Israel
| | - Akiva Feintuch
- Department of Chemical and Biological Physics , Weizmann Institute of Science , Rehovot - 76100 , Israel
| | - Shimon Vega
- Department of Chemical and Biological Physics , Weizmann Institute of Science , Rehovot - 76100 , Israel
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268
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Plainchont B, Berruyer P, Dumez JN, Jannin S, Giraudeau P. Dynamic Nuclear Polarization Opens New Perspectives for NMR Spectroscopy in Analytical Chemistry. Anal Chem 2018; 90:3639-3650. [PMID: 29481058 DOI: 10.1021/acs.analchem.7b05236] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Dynamic nuclear polarization (DNP) can boost sensitivity in nuclear magnetic resonance (NMR) experiments by several orders of magnitude. This Feature illustrates how the coupling of DNP with both liquid- and solid-state NMR spectroscopy has the potential to considerably extend the range of applications of NMR in analytical chemistry.
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Affiliation(s)
- Bertrand Plainchont
- Université de Nantes , CNRS, CEISAM UMR 6230 , 44322 Nantes Cedex 03 , France
| | - Pierrick Berruyer
- Université Claude Bernard Lyon 1, CNRS, ENS de Lyon , Institut des Sciences Analytiques, UMR 5280 , 5 Rue de la Doua , 69100 Villeurbanne , France
| | - Jean-Nicolas Dumez
- Institut de Chimie des Substances Naturelles, CNRS UPR 2301 , Univ. Paris Sud, Université Paris-Saclay , 91190 Gif-sur Yvette , France
| | - Sami Jannin
- Université Claude Bernard Lyon 1, CNRS, ENS de Lyon , Institut des Sciences Analytiques, UMR 5280 , 5 Rue de la Doua , 69100 Villeurbanne , France
| | - Patrick Giraudeau
- Université de Nantes , CNRS, CEISAM UMR 6230 , 44322 Nantes Cedex 03 , France.,Institut Universitaire de France , 75005 Paris , France
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269
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Sani MA, Martin PA, Yunis R, Chen F, Forsyth M, Deschamps M, O'Dell LA. Probing Ionic Liquid Electrolyte Structure via the Glassy State by Dynamic Nuclear Polarization NMR Spectroscopy. J Phys Chem Lett 2018; 9:1007-1011. [PMID: 29420892 DOI: 10.1021/acs.jpclett.8b00022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Dynamic nuclear polarization (DNP)-enhanced solid-state NMR spectroscopy has been used to study an ionic liquid salt solution (N-methyl-N-propyl-pyrrolidinium bis(fluorosulfonyl)imide, C3mpyrFSI, containing 1.0 m lithium bis(fluorosulfonyl)imide, 6LiFSI) in its glassy state at a temperature of 92 K. The incorporation of a biradical to enable DNP signal enhancement allowed the proximities of the lithium to the individual carbon sites on the pyrrolidinium cation to be probed using a 13C-6Li REDOR pulse sequence. Distributions in Li-C distances were extracted and converted into a 3D map of the locations of the Li+ relative to the C3mpyr that shows remarkably good agreement with a liquid-phase molecular dynamics simulation.
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Affiliation(s)
- Marc-Antoine Sani
- School of Chemistry, Bio21 Institute, University of Melbourne , Melbourne, Victoria 3010, Australia
| | - Pierre-Alexandre Martin
- Institute for Frontier Materials, Deakin University , Geelong, Victoria 3220, Australia
- CEMHTI, CNRS UPR 3079, Université d'Orléans , F45071 Orléans, France
- RS2E, FR CNRS 3459 , 80039 Amiens, France
| | - Ruhamah Yunis
- Institute for Frontier Materials, Deakin University , Geelong, Victoria 3220, Australia
| | - Fangfang Chen
- Institute for Frontier Materials, Deakin University , Geelong, Victoria 3220, Australia
| | - Maria Forsyth
- Institute for Frontier Materials, Deakin University , Geelong, Victoria 3220, Australia
| | - Michaël Deschamps
- CEMHTI, CNRS UPR 3079, Université d'Orléans , F45071 Orléans, France
- RS2E, FR CNRS 3459 , 80039 Amiens, France
| | - Luke A O'Dell
- Institute for Frontier Materials, Deakin University , Geelong, Victoria 3220, Australia
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270
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Abstract
Various recent developments in solid-state nuclear magnetic resonance (ssNMR) spectroscopy have enabled an array of new insights regarding the structure, dynamics, and interactions of biomolecules. In the ever more integrated world of structural biology, ssNMR studies provide structural and dynamic information that is complementary to the data accessible by other means. ssNMR enables the study of samples lacking a crystalline lattice, featuring static as well as dynamic disorder, and does so independent of higher-order symmetry. The present study surveys recent applications of biomolecular ssNMR and examines how this technique is increasingly integrated with other structural biology techniques, such as (cryo) electron microscopy, solution-state NMR, and X-ray crystallography. Traditional ssNMR targets include lipid bilayer membranes and membrane proteins in a lipid bilayer environment. Another classic application has been in the area of protein misfolding and aggregation disorders, where ssNMR has provided essential structural data on oligomers and amyloid fibril aggregates. More recently, the application of ssNMR has expanded to a growing array of biological assemblies, ranging from non-amyloid protein aggregates, protein–protein complexes, viral capsids, and many others. Across these areas, multidimensional magic angle spinning (MAS) ssNMR has, in the last decade, revealed three-dimensional structures, including many that had been inaccessible by other structural biology techniques. Equally important insights in structural and molecular biology derive from the ability of MAS ssNMR to probe information beyond comprehensive protein structures, such as dynamics, solvent exposure, protein–protein interfaces, and substrate–enzyme interactions.
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271
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Liao WC, Ghaffari B, Gordon CP, Xu J, Copéret C. Dynamic Nuclear Polarization Surface Enhanced NMR spectroscopy (DNP SENS): Principles, protocols, and practice. Curr Opin Colloid Interface Sci 2018. [DOI: 10.1016/j.cocis.2018.02.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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272
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Neugebauer P, Bloos D, Marx R, Lutz P, Kern M, Aguilà D, Vaverka J, Laguta O, Dietrich C, Clérac R, van Slageren J. Ultra-broadband EPR spectroscopy in field and frequency domains. Phys Chem Chem Phys 2018; 20:15528-15534. [DOI: 10.1039/c7cp07443c] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electron paramagnetic resonance (EPR) is a powerful technique to investigate the electronic and magnetic properties of a wide range of materials.
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273
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Rogawski R, Sergeyev IV, Zhang Y, Tran TH, Li Y, Tong L, McDermott AE. NMR Signal Quenching from Bound Biradical Affinity Reagents in DNP Samples. J Phys Chem B 2017; 121:10770-10781. [PMID: 29116793 PMCID: PMC5842680 DOI: 10.1021/acs.jpcb.7b08274] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We characterize the effect of specifically bound biradicals on the NMR spectra of dihydrofolate reductase from E. coli. Dynamic nuclear polarization methods enhance the signal-to-noise of solid state NMR experiments by transferring polarization from unpaired electrons of biradicals to nuclei. There has been recent interest in colocalizing the paramagnetic polarizing agents with the analyte of interest through covalent or noncovalent specific interactions. This experimental approach broadens the scope of dynamic nuclear polarization methods by offering the possibility of selective signal enhancements and the potential to work in a broad range of environments. Paramagnetic compounds can have other effects on the NMR spectroscopy of nearby nuclei, including broadening of nuclear resonances due to the proximity of the paramagnetic agent. Understanding the distance dependence of these interactions is important for the success of the technique. Here we explore paramagnetic signal quenching due to a bound biradical, specifically a biradical-derivatized trimethoprim ligand of E. coli dihydrofolate reductase. Biradical-derivatized trimethoprim has nanomolar affinity for its target, and affords strong and selective signal enhancements in dynamic nuclear polarization experiments. In this work, we show that, although the trimethoprim fragment is well ordered, the biradical (TOTAPOL) moiety is disordered when bound to the protein. The distance dependence in bleaching of NMR signal intensity allows us to detect numerous NMR signals in the protein. We present the possibility that static disorder and electron spin diffusion play roles in this observation, among other contributions. The fact that the majority of signals are observed strengthens the case for the use of high affinity or covalent radicals in dynamic nuclear polarization solid state NMR enhancement.
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Affiliation(s)
- Rivkah Rogawski
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Ivan V Sergeyev
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Yinglu Zhang
- Department of Biological Sciences, Columbia University , New York, New York 10027, United States
| | - Timothy H Tran
- Department of Biological Sciences, Columbia University , New York, New York 10027, United States
| | - Yongjun Li
- Department of Chemistry, Columbia University , New York, New York 10027, United States
| | - Liang Tong
- Department of Biological Sciences, Columbia University , New York, New York 10027, United States
| | - Ann E McDermott
- Department of Chemistry, Columbia University , New York, New York 10027, United States
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